Tire sidewall deformation detection techniques

ABSTRACT

An improvement in a tire manufacturing system including means for testing the extent of sidewall deformation of a tire. The tire is rotated and measured for lateral runout of both sidewalls. The resulting data is converted to digital form and analyzed by groups in order to increase the accuracy by which unacceptable sidewall bulges and valleys are detected.

BACKGROUND AND SUMMARY

This invention relates to the manufacture of vehicle tires and moreparticularly relates to the portion of the manufacturing process bywhich the quality of the tire sidewalls is maintained.

The tire industry has long sought an automated method of improving thequality of single-ply tires. Such tires weigh less and cost less thanmultiple ply tires and therefore are particularly attractive for use onlight-weight economy vehicles.

While single-ply tires have become attractive for use on economy cars,certain problems inherent with those tires have become apparent. Aparticular problem evolves from irregularities in the ply splice at thesidewall of the tire. If this splice is other than a flush butt fit, thesidewall at the splice may exhibit undesired characteristics. Forexample, if the splice is lapped, the sidewall becomes exceptionallystrong at that point, being effectively a double-ply at the splice. Wheninflated, the sidewall at the splice may not expand to the same degreeas the sidewall as a whole, thus generating a deformation commonlytermed a "valley." While this valley is an indication of exceptionalstrength at that point of the sidewall, if the valley is excessive, itbecomes unsightly and therefore unmarketable. In the case of an opensplice, the sidewall is weakened such that, when inflated, the weakenedarea at the splice will excessively expand to define a deformationcommonly termed a "bulge." Such a bulge is not only an indication of aweakened area in the sidewall, but becomes unsightly if excessive.

Bulges and valleys are peculiar to single or mono-ply tires, since tiresof multiple plies are typically of sufficient strength to be unaffectedby an open or lapped splice in any of the plies. In a single ply tire,an open splice results in reduced ply strength at the affected area ofthe sidewall, while a lapped splice results in an effective doubling ofthe strength at that area.

Since the undesirability of a bulge or valley is partially aesthetic,different users of the tires will have different specifications fordetermining the maximum dimensions of valleys or bulges (or both) whichare acceptable. Ideally, the tire quality control portion of themanufacturing process should be conveniently adaptable to differentspecifications.

There have been several teachings in the art of apparatus for sensingand testing the dimensional characteristics of a tire. Applicant isaware of U.S. Pat. Nos. 3,895,518; 3,303,571; and 2,25,803, all of whichteach a technique for monitoring the sidewall of a tire. However, eachof these patents is of a rudimentary mechanical nature, capable ofsensing only that the sidewall of a mounted tire has exceeded the limitunassociated with the tire itself.

U.S. Application Ser. No. 270,087, entitled "Method And Apparatus ForTire Sidewall Bulge And Valley Detection", filed June 3, 1981 in thename of Jean Engel and assigned to the assignee of the presentapplication, discloses an improvement in the art of detecting sidewalldeformations by measuring the slope of the sidewall bulges or valleyswith analog circuitry. However, this technique is somewhat less accuratethan desired for certain applications, especially if the quality controlspecification for the tire requires that a bulge be distinguished from avalley.

Accordingly, it is a primary object of the present invention to improvethe manufacture of tires by furnishing an automated digital techniquefor accurately and rapidly determining the extent of sidewalldeformations in a tire.

Another object is to provide a technique of the foregoing type capableof distinguishing sidewall bulges from valleys.

Still another object is to provide a technique of the foregoing type inwhich test criteria can be rapidly and accurately changed to accommodatedifferent tire specifications.

Yet another object is to provide a technique of the foregoing type inwhich different limits can be used to detect excessive bulges andvalleys.

In order to achieve these objectives, the applicant has totally departedfrom the analog differentiating and slope comparing circuitry of Engel.The applicant has discovered that digital circuitry, including a memoryand processor, provides more accurate results. According to one aspectof the invention, the processor divides data from the tire sidewall intoa plurality of groups which are individually analyzed. The results arethen combined and compared with a predetermined limit which can bereadily altered. By these techniques, the condition of a tire can beindicated with a degree of accuracy and reliability previouslyunobtainable.

DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and features of the invention willappear for purposes of explanation, but not limitation, in connectionwith the accompanying drawings wherein like numbers refer to like partsthroughout and wherein:

FIG. 1 is a schematic flow diagram of an exemplary method ofmanufacturing a vehicle tire;

FIG. 2 is a fragmentary, side elevational view of a conventional tireforce variation measuring and grinding machine adapted to providecertain input measurement signals required by the preferred embodimentof the invention;

FIG. 3 is another view of the apparatus shown in FIG. 2 in which a tireis mounted and inflated, and tracking probes are positioned to providethe input measurement signals;

FIG. 4 is an enlarged perspective view of the tire mounted and inflated;

FIG. 5 is a schematic view of the tire shown in FIG. 4 illustrating theplacement of a tracking probe on the sidewall of the tire;

FIG. 6 is an electrical schematic block diagram illustrating a preferredform of processing and memory apparatus for use in connection with thepreferred embodiment as connected to the tracking probes;

FIGS. 7A and 7B are flow diagrams illustrating a preferred form ofprogram for the processing apparatus shown in FIG. 6;

FIG. 8 is a timing diagram illustrating how some of the steps in theflow diagrams of FIGS. 7A and 7B operate on exemplary groups of inputdata; and

FIG. 9 is a schematic side elevation of a preferred form of tire markingand gating apparatus for use in connection with the preferredembodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, eight basic steps of manufacturing a vehicle tireare shown in blocks M1-M8. In step M1, rubber compounds are mixed andsome tire fabric is coated with the compounds. In addition, variouscomponent parts of the tire, such as tread and belts, are fabricated andcut to proper size. In step M2, the prepared components are assembledtogether on a mandrel. In step M3, the assembled components are cured,thereby solidifying the component parts into a unified whole. In stepM4, raw edges created during the curing process are cut or ground and,in some cases, letters and other indicia are cut into the sidewall ofthe tire. In step M5, the tire is tested for defects, an important partof the overall manufacturing process which is critical for single plytires. In step M6, tires with defects, if any, are indicated. Twomethods of indication are: (1) marking the defective tire with anappropriate indicia, or (2) segregating defective tires from good tires.In step M7, the tires are packaged in preparation for shipment to acustomer (step M8).

Referring to FIGS. 2 and 3, a portion of testing step M5 may be carriedout by a tire force variation measuring and grinding machine suitablyadapted for tracking probes which measure the lateral runout on each ofthe two sidewalls of a cured tire. Such machines are well known in theart, and need not be described in detail. One such machine is shown inU.S. Application Ser. No. 188,707, entitled "Tire Dynamic ImbalanceScreening System", filed Sept. 19, 1980 in the names of Kounkel et al.,and assigned to the same assignee as the present application. Asdescribed in more detail in that application, a force variation testingmachine 110 has an upper chuck 111 rotatably mounted on an upper frame112. A lower frame 113 supports a vertical spindle 114 for rotation andvertical movement in a sleeve 115 attached to the frame. A lower chuck116 is mounted on spindle 114 and is axially movable from an openretracted position shown in FIG. 2 to a closed extended position shownin FIG. 3.

Tracking probes 118a and 118b capable of generating an analog signalproportional to the lateral runout of the tire sidewalls preferablyinclude a tip 117a and a tip 117b. The probes are connected torotational displacement transducers mounted on upper frame 112 and lowerframe 113 for engagement with a tire 119 mounted between chucks 111 and116 as shown in FIG. 3. Probes 118a and 118b are carried by measuringmechanism supports 120a and 120b, respectively, which are verticallyadjustable relative to upper frame 112 and lower frame 113 to provideclearance for movement of tire 119 between upper chuck 111 and lowerchuck 116. The vertical adjustment may be provided by air-actuatedpiston and cylinder apparatus mounted on frames 112 and 113 which carrythe measuring mechanism supports 120a and 120b from retracted positionsshown in FIG. 2 to extended positions, shown in FIG. 3, with tips 117aand 117b in contact with tire 119.

Tire inflating apparatus, such as a port (not shown) in one of chucks111 or 116 is also provided for communication between the space enclosedby tire 119 and a source of air pressure. A load roller 123 is movableradially of tire 119 into engagement with the tread of the tire and maybe used to seat the tire on the bead seats of upper chuck 111 and lowerchuck 116.

As an alternative to tips 117a and 117b, proximity sensors 124a and 124bmay be carried on the measuring mechanism supports 120a and 120b forvertical adjustment into positions spaced from the tire. Sensors 124aand 124b provide signals indicating lateral runout as tire 119 isrotated on chucks 111 and 116.

Referring to FIG. 5, probe 118a is shown in more detail. Probe 118b isidentical to probe 118a and may be understood with reference to FIG. 5.Probe 118a comprises an aluminum arm 126 bearing a carbide tip 117a. Thearm rotates with an axle or pin 128 and is biased by a spring (notshown) which urges the arm toward the tire sidewall. The arm is made aslight as possible and the spring force is the minimum needed to causethe tip to follow the undulations in the sidewall of the tire. Rotationof arm 126 caused by contact with tire 119 causes pin 128 to rotateinside a resolver 130. The resolver acts as a transducer which convertsthe movement of the probe against the sidewall of the rotating tire intoa corresponding analog signal on output conductor 134 (FIG. 6). Thesignal has a value proportional to the vertical position of the tiresidewall. A similar signal for the opposite sidewall is produced on aconductor 136 connected to the transducer associated with probe 118b(FIG. 6). Additional details of resolver 130 are described in theabove-identified Engel application.

Tire 119 is typically carried to machine 110 by an automatic conveyorand is automatically positioned upon lower chuck 116, inflated, andcaused to rotate by contact with rotating roller 123. A pulse generator125 (FIG. 6) attached to spindle 114 generates an electrical pulse eachtime the tire rotates through one degree of arc (360 pulses perrevolution) and transmits the pulse over a conductor 127. Probes 118aand 118b are then brought into contacting engagement with oppositesidewalls W1 and W2 of the tire. As shown in FIG. 5, the probes track arelatively thin section of the sidewalls about a circumference which isunobstructed by lettering or other molded depressions or protusions suchthat the movement of the probes are characteristic of deflections of thesidewalls themselves. As tire 119 is rotated, probes 118a and 118b rideon the sidewalls of the tire, and the transducers associated with theprobes produce analog signals having values proportional to the lateralrunout of the sidewalls. Thus, the probes are able to detect a bulge Bor a valley V (FIG. 4).

In the event there are undesired deformations in sidewall W1, adimension LR1 extending from plane P to the outside of the sidewall willexperience fluctuations (FIG. 3). Likewise, if there are undesireddeformations in sidewall W2, the lateral runout dimension LR2 betweenplane P and the outside of sidewall W2 will fluctuate. As shown in FIG.3, plane P is perpendicular to the axis of rotation of the tire andpasses through the center of the tire thereby dividing the tire into twoequal sections with bilateral symmetry.

Referring to FIG. 6, tracking probes 118a and 118b are connected to acomputer or processing device 140. Preferably the computer comprises amodel HP 1,000 L-series manufactured by Hewlett-Packard Corporation.This computer has a random access memory 142, an analog input card 144which contains an analog-to-digital converter, and a digital output card145 which provides signals to gating and marking devices shown in FIG.9. As shown in FIG. 6, the tracking probes are connected throughconductors 134 and 136 to the analog input card of the computer. Thecomputer also contains a terminal 150 which is preferably a model HP2645a also manufactured by Hewlett-Packard Corporation. The terminalcontains a CRT display 152 and a keyboard 154. The terminal is connectedto computer 140 through a conventional buss 156 supplied byHewlett-Packard.

Referring to FIG. 9, tire 110 is carried to testing machine 110 by aconventional conveyor 160. If the tire is defective, it is conveyed to aconveyor 162; if the tire is acceptable, it is conveyed to a conveyor164. Proper conveying of the tire is achieved through a gating mechanism166 comprising a conveyor 168 which is rotated around an axis 170 by apneumatic controller 172. Controller 172 includes a cylinder 174 fittedwith a piston 176 which raises or lowers a connecting rod 178.Compressed air is admitted to the upper or lower sides of the piston bya valve 180 controlled by a logical gating signal transmitted over aconductor 182.

The tire can be marked with ink by means of a marking mechanism 184comprising 8 stamping plates 186 which are primed by an ink supply 188.Eight solenoids 190 (one for each plate) are capable of depressingindividual plates into contact with the tire. By energizing combinationsof solenoids, 28 different patterns of marks can be placed on the tire.The solenoids are controlled by an 8-bit buss 192 connected to computer140 (FIG. 6).

Referring to FIG. 7A, the computer is programmed to convert the analogsignals received on conductors 134 and 136 into digital form, to storethose signals in a random access memory 142, to process the signals in aunique manner, and to indicate whether the deformations of eithersidewall W1 or sidewall W2 exceed limits which can be inserted into theprogram by the operator.

As shown in step S19, the operator stores the maximum allowable bulgelimit and the minimum allowable valley limit through operation ofkeyboard 154 and display 152. Preferably, the bulge limit is 20 and thevalley limit is 25, although other limits can be inserted depending onthe desired tire specifications. These limits need to be reset only oncefor each different batch of tires, and then only if the tirespecifications require different limits.

In step S20, the computer samples and stores in digital form 360 valuesfrom sidewall W1 and 360 values from sidewall W2 (FIG. 3). One value foreach of sidewalls W1 and W2 designated "IVAL", is stored for each degreeof rotation of tire 119. Thus 360 values correspond to the entire 360degree arc of sidewall W1, and a like number of values correspond to theentire 360 degree arc of sidewall W2. The first 36 of these values forsidewall W1 are represented in FIG. 8. Each of the values can bedesignated by a variable IVAL which is established by the computerprogram.

In step S21, the program establishes an initial reference base bysumming values of IVAL stored in memory for sidewall W1 from the value 1through the value of a variable IWIDE. IWIDE preferably equals 31, butuseful results can be obtained by IWIDE values between 10 and 100(corresponding to sidewall arcs between 10 degrees and 100 degrees),depending on the type of tire defect being detected. Assuming IWIDEequals 31, the first 31 lateral runout values (IVAL) are summed by thecomputer and stored as variable IWSUM. As shown in FIG. 8, IWSUM for thefirst 31 degrees of rotation equals 140.

In step S22, other initial values used in connection with the firstgroup of lateral runout values are established. That is, computervariables ISTRT, ICENTR and IFINI are established. As shown in FIG. 8,these values for the first group of 31 lateral runout values equal 1, 16and 31, respectively.

In step S23, a program variable IBULG, corresponding to the initialsidewall bulge deformation, is set equal to 0, and the program variableIVALY, corresponding to the initial sidewall valley deformation, is setequal 0. Reference values for 360 different groups of lateral runoutvalues are ultimately calculated, and a variable IGROP is established asa software counter to keep track of how many groups have beencalculated. The counter is initially set equal to 0.

In step S24, the reference value IWSUM is compared to the lateral runoutvalue at degree 16 (i.e., value ICNTR) multiplied times IWIDE. Thedifference is a group deformation value (NEWVAL) indicative of thedegree of deformation corresponding to the lateral runout valuesrepresented by the first 31 degrees of rotation. As shown in FIG. 8, thefirst NEWVAL value (NEWVAL₁) is 108.

NEWVAL is then compared with the current value of IBULG in order todetermine whether a new bulge value should be stored. According to stepS25, a new bulge value is indicated if the current value of NEWVALexceeds the current value of IBULG. If so, the new value is stored as anew IBULG value in step S26. Since 108 (NEWVAL₁) is greater than 0(IBULG), the value of IBULG is changed to 108.

If a new bulge value does not result from step S25, the current value ofNEWVAL is compared with the current value of IVALY in step S27. If IVALYexceeds NEWVAL, a new valley value is stored in step S28. In the initialstep described so far, if NEWVAL is a positive number, it indicates anew bulge value; if it is a negative number, it indicates a new valleyvalue.

In step S29, the program determines whether the variable IGROP equals360. Since only one group of lateral runout values has been consideredat this point in time, the answer is no, and the program moves on tostep S30.

Referring to FIG. 7B, steps S30-32 are used to calculate a new groupvalue corresponding to the lateral runout values representing degrees2-32 of sidewall rotation. In other words, while the initial groupcorresponded to degrees 1-31 of rotation, the next group underconsideration corresponds to degrees 2-32. This portion of the programcan be analogized to a 31 degree-wide window which is placed over thetire in order to analyze lateral runout values which show through thewindow. The window is then rotated 1 degree so that one of the formervalues is covered up and a new value is exposed. By subtracting thecovered up value and adding the newly exposed value, the sum of thevalues for the new group can be quickly determined without performingthe complete summation required in step S21. In accordance with thisapproach, in step S30, the first point of the old reference group (i.e.,IVAL corresponding to rotation degree 1) is stored so that it can belater subtracted from the total group value.

In step S31, pointers for the same values calculated in step S22 areindexed by 1 by means of a modulus operator MOD. This is a standardFORTRAN function which subtracts 360 before indexing in the event thevariable exceeds 360. This is needed so that the proper values will becalculated when the window wraps around the entire circumference of thetire and uses some of the initial starting values in the groupcorresponding to degrees 1-31.

In step S32, a new reference value is calculated by subtracting the old"covered up" value (IOVAL) and adding the "newly exposed" value (i.e.,IVAL at degree 32) and storing the resulting value as variable IWSUM. Asshown in FIG. 8, IWSUM₂ for the second group (degrees 2-32) is still140. After the new reference value for the new group of lateral run outvalues has been calculated in step S32, the program indexes variableIGROP in step S33 (FIG. 7A). The program then returns to step S24 inorder to calculate a new group value (NEWVAL) for the second group.NEWVAL for the second group (NEWVAL₂) is calculated to be 232 (see FIG.8). Since NEWVAL₂ is greater than the previous value for IBULG (i.e.108), 232 is stored as the new value for IBULG in step S26. The programthen proceeds through steps S27-S33 as previously described.

After 360 groups of values have been considered, the variable IGROPequals 360, and the program branches to step S34 (FIG. 7B). In step S34,the IBULG and IVALY variables are scaled by dividing by 31 (the value ofIWIDE) in order to prepare these values for proper comparison with thebulge and valley limits established in step S19.

In step S35, the scaled IBULG and IVALY values are stored for latercomparison to limits.

In step S36, steps S21-S35 are repeated for lateral runout values ofsidewall W2, and the values scaled in step S35 are stored as valuesIBULG (W2) and IVALY (W2).

If IBULG (W2) is not greater than IBULG (W1), the variable IBULG is setequal to the scaled IBULG value for sidewall W1 in steps S37 and S38.The operation is performed on the scaled IVALY values for sidewalls W1and W2 in steps S39 and S40.

According to step S41, if the value of IBULG is greater than the bulgelimit established in step S19, a BULGE flag is set in step S42. If thevalue of IVALY is greater than the valley limit established in steps S19(step S43), a VALLEY flag is set in step S44. The IBULG and IVALY valuesused in steps S41 and S43 are indicative of the degree of deformation insidewalls W1 and W2 as a whole, and can be used as an accurate measureof the condition of the tire resulting from the component preparation,assembly, and curing steps of the manufacturing process (FIG. 1).

In step S45, the program returns to step S20 to repeat the sequencedescribed above in connection with the next tire.

In response to the setting of the BULGE flag in step S42, the markingapparatus shown in FIG. 9 can be initiated through buss 192 in order tomark the tire with indicia indicating the presence of an unacceptablebulge. Likewise, in response to the setting of the VALLEY flag in stepS44, the same apparatus can be set through buss 192 to mark the tirewith indicia indicating the presence of an unacceptable valley in thesidewall. Similarly, a logical one signal can be transmitted overconductor 182 in order to raise conveyor gate 168 to a position adjacentconveyor 164 in order to segregate a tire having an unacceptable bulgeor valley from the tires which are acceptable.

Although the best mode of the invention known to the applicant has beendescribed herein, those skilled in the art will recognize that the bestmode may be altered and modified without departing from the true spiritand scope of the invention as defined in the accompanying claims.

What is claimed is:
 1. In a tire manufacturing system including meansfor assembling and curing components of the tire and for testing thecured tire by detecting lateral runout values for at least one sidewallof the tire, improved apparatus for determining the degree of side walldeformation resulting from the assembling and curing, said apparatuscomprising:storage means for storing a plurality of the lateral runoutvalues; processing means for segregating the lateral runout values intoa plurality of groups, each group representing a portion of thesidewall, for calculating a reference value for each group based on atleast a portion of the runout values within the group, for comparing thereference values to at least one of the laterial runout values in thegroup in order to generate a group deformation value indicative of thedegree of deformation in the portion of the sidewall represented by thegroup, and for generating a deformation flag signal if any of the groupdeformation values generated for the various groups have a predeterminedrelationship with respect to a predetermined limit; and means forindicating the condition of the tire in response to the deformation flagsignal.
 2. Apparatus, as claimed in claim 1, wherein the lateral runoutvalues are detected by generating an analog signal and wherein theapparatus further comprises means for converting the analog signal todigital signals representing a plurality of the lateral runout values.3. Apparatus, as claimed in claim 2, wherein the storage means comprisesa digital memory.
 4. In tire testing apparatus capable of generating ananalog signal corresponding to the lateral runout values for at leastone sidewall of a tire, improved means for determining the degree ofdeformation present in the sidewall of the tire comprising:means forconverting the analog signal to digital signals representing a pluralityof the lateral runout values; storage means for storing a plurality ofthe digital signals corresponding to digital lateral runout values;processing means for segregating the lateral runout values into aplurality of groups, each group representing a portion of the sidewall,for calculating a reference value for each group based on at least aportion of the runout values within the group, for comparing thereference value to at least one of the lateral runout values in thegroup in order to generate a group deformation value indicative of thedegree of deformation in the portion of the sidewall represented by thegroup, and for generating a deformation flag signal if any of the groupdeformation values generated for the various groups have a predeterminedrelationship with respect to a predetermined limit; and means forindicating the condition of the tire in response to the deformation flagsignal.
 5. Apparatus, as claimed in claims 1 or 4, wherein theprocessing means comprises means for generating a group deformationvalue of a first polarity indicative of a sidewall bulge and forgenerating a group deformation value of a second polarity opposite thefirst polarity indicative of a sidewall valley.
 6. Apparatus, as claimedin claim 5, wherein the processing means comprises means for comparingthe group deformation values in order to generate a first resultantdeformation value indicative of the maximum bulge for the sidewall as awhole, for generating a second resultant deformation value indicative ofthe minimum valley for the sidewall as a whole, for comparing the firstresultant deformation value to a first predetermined limit and forcomparing the second resultant deformation value to a secondpredetermined limit, andwherein the means for indicating comprises meansfor indicating the condition of the tire based on the comparison of thefirst resultant deformation value to the first predetermined limit andthe comparison of the second resultant deformation value to the secondpredetermined limit.
 7. Apparatus, as claimed in claims 1 or 4, whereinthe processing means comprises means for defining each of said groups torepresent 10 to 100 degrees of sidewall arc.
 8. Apparatus, as claimed inclaim 7, wherein the processing means comprises means for defining eachof said groups to represent 31 degrees of sidewall arc.
 9. Apparatus, asclaimed in claims 1 or 4, wherein the processing means comprises meansfor defining the groups to represent overlapping portions of thesidewall.
 10. Apparatus, as claimed in claims 1 or 4, wherein theprocessing means comprises means for calculating the reference value bysumming the values in the group.
 11. Apparatus, as claimed in claims 1or 4, wherein the processing means comprises means for adjusting thepredetermined limit.
 12. Apparatus, as claimed in claim 6, wherein theprocessing means comprises means for adjusting the first and secondpredetermined limits.
 13. Apparatus, as claimed in claims 1 or 4,wherein the means for indicating comprises means for marking the tire.14. Apparatus, as claimed in claims 1 or 4, wherein the means forindicating comprises means for gating the tire.
 15. In a tiremanufacturing method including assembling and curing the tire andtesting the cured tire by detecting lateral runout values for at leastone sidewall of the tire, an improved process for determining the degreeof sidewall deformation resulting from the assembling and curingcomprising the steps of:storing a plurality of the lateral runoutvalues; segregating the lateral runout values into a plurality ofgroups, each group representing a portion of the sidewall; calculating areference value for each group based on at least a portion of the runoutvalues within the group; comparing the reference value to at least oneof the lateral runout values in the group in order to generate a groupdeformation value indicative of the degree of deformation in the portionof the sidewall represented by the group; generating a deformation flagsignal if any of the group deformation values generated for the variousgroups have a predetermined relationship with respect to a predeterminedlimit; and indicating the condition of the tire in response to thedeformation flag signal.
 16. A process, as claimed in claim 15, whereinthe lateral runout values are detected by generating an analog signaland wherein the process further comprises the step of converting theanalog signal to digital signals representing a plurality of the lateralrunout values.
 17. A process, as claimed in claim 16, wherein the stepof storing comprises the step of storing digital values.
 18. In thetesting method capable of generating an analog signal corresponding tothe lateral runout values for at least one sidewall of a tire, animproved process for determining the degree of deformation present inthe sidewall of the tire comprising the steps of:converting the analogsignal to digital signals representing a plurality of the lateral runoutvalues; segregating the lateral runout values into a plurality ofgroups, each group representing a portion of the sidewall; calculating areference value for each group based on at least a portion of the runoutvalues within the group; comparing the reference value to at least oneof the lateral runout values in the group to order to generate a groupdeformation value indicative of the degree of deformation in the portionof the sidewall represented by the group; generating a deformation flagsignal if any of the group deformation values generated for the variousgroups have a predetermined relationship with respect to a predeterminedlimit; and indicating the condition of the tire in response to thedeformation flag signal.
 19. A process, as claimed in claims 15 or 18,wherein generation of the group deformation value comprises the stepsof:generating a group deformation value of a first polarity indicativeof a sidewall bulge; and generating a group deformation value of asecond polarity opposite the first polarity indicative of a sidewallvalley.
 20. A process, as claimed in claim 19, and further comprisingthe steps of:comparing the group deformation values in order to generatea first resultant deformation value indicative of the maximum bulge forthe sidewall as a whole; generating a second resultant deformation valueindicative of the minimum valley for the sidewall as a whole; comparingthe first resultant deformation value to a first predetermined limit;comparing the second resultant deformation value to a secondpredetermined limit; and indicating the condition of the tire based onthe comparison of the first resultant deformation value to the firstpredetermined limit and the comparison of the second resultantdeformation value to the second predetermined limit.
 21. A process, asclaimed in claim 20, and further comprising the step of adjusting thefirst and second predetermined limits.
 22. A process, as claimed inclaims 15 or 18 and further comprising the step of defining each of saidgroups to represent 10 to 100 degrees of sidewall arc.
 23. A process, asclaimed in claim 22, and further comprising the step of defining each ofsaid groups to represent 31 degrees of sidewall arc.
 24. A process, asclaimed in claims 15 or 18, and further comprising the step of definingthe groups to represent overlapping portions of the sidewall.
 25. Aprocess, as claimed in claims 15 or 18, and further comprising the stepof calculating the reference value by summing the values in the group.26. A process, as claimed in claims 15 or 18, and further comprising thestep of adjusting the predetermined limit.
 27. A process, as claimed inclaims 15 or 18, wherein the step of indicating comprises marking thetire.
 28. A process, as claimed in claims 15 or 18, wherein the step ofindicating comprises gating the tire.